24 November 2014

T.J. McFarland's Tricky Platoon Split

Platoon splits are weird things. They often don't reflect a player's true talent level, meaning we must heavily regress them to get a more accurate projection. (Like many things in baseball, this applies even more when the sample size is small.) I don't take a bold stand by saying that — all sabermetricians agree on it. But the means by which we look at a player, particularly a pitcher, and determine if he has a platoon split can lead to fallacious thinking. While most people utilize the numbers of opposing batters, they should probably rely on pitching-oriented numbers instead, because the former can deceive.

T.J. McFarland illustrates this conundrum pretty well. Does he have a platoon split? By some statistics, no. For his career, he's faced 244 left-handed batters, who have a .322 wOBA against him; the 342 right-handed batters to whom he's pitched only top that by three points (.325). That's really not much of a difference at all, and most projections would reflect that. So we can expect him to consistently retire batters of any handedness going forward, right?

Well, about that. Those same lefties have struck out in 21.7% of their plate appearances, while walking a mere 5.3% of the time; when they've put the ball in play, it stays on the ground 63.3% of the time. By contrast, the righties own marks of 11.4%, 8.2%, and 57.4%, respectively, in those regards. Put it all together, and McFarland has a career xFIP of 2.77 against same-handed hitters, to go along with a career xFIP of 4.32 against opposite-handed hitters.

His repertoire corroborates the xFIP side of the story: The two pitches on which he leans the most — his sinker (65.1% of career pitches) and slider (19.5%) — also have two of the largest platoon splits among common pitches. In other words, sinker-slider pitchers will almost certainly have a significant platoon split. His increased implementation of his changeup against righties (18.5% against them, 0.4% against lefties) can compensate some, but as the aforementioned plate discipline and batted-ball marks show, it can't do it all.

Why does this matter, though? Maybe McFarland's wOBA splits do a better job of reflecting his true talent level than his xFIP. A closer examination of the splits reveals that to be, in all likelihood, false. The discrepancy between the two splits comes almost entirely as the result of home runs. Of the nine he's allowed since debuting last year, left-handed batters have hit five, despite facing him far less often than right-handed batters. With lower fly ball rates, they've done this by making the most of the few fly balls they do hit: Their HR/FB% of 16.7% dwarfs the 6.2% figure their opposition has posted. Since HR/FB% is a notoriously fluky statistic, especially with a sample as minuscule as this, this almost certainly doesn't have anything to it.

So what does this mean going forward? For the past two campaigns, McFarland has served as a solid long reliever, someone whom the team could trust to pitch effectively against any batter. In the coming seasons, however, that might not hold true; if it doesn't, McFarland could see his role reduced to a one-inning guy, or even a lowly LOOGY. He shouldn't decline notably overall — Steamer projects a 3.46 ERA and 3.64 FIP, in line with his career numbers of 3.58 and 3.59, respectively — but the good fortune that he's had so far, and that has given him the veneer of an equal-opportunity hurler, will probably come to an end.

Contact Camden Depot

We look forward to your questions as well as any suggestions you may have for us.

Additionally, we are always looking for new contributors, so if you want to write for the Depot then e-mail us with an example column that you think fits the tone of the site.

Contributors

Jon Shepherd - Founder/Editor@CamdenDepotStarted Camden Depot in the summer of 2007. By day, a toxicologist and by night a baseball analyst. His work is largely located on this site, but may pop up over at places like ESPN or Baseball Prospectus.

Matt Kremnitzer - Assistant Editor@mattkremnitzerMatt joined Camden Depot in early 2013. His work has been featured on ESPN SweetSpot and MASNsports.com.

Matthew Cassidy - WriterMatt joined Camden Depot before Spring Training in 2017. His love of music is surpassed only by his obsessions with food (unhealthy) and baseball statistics (totally healthy).

Patrick Dougherty - Writer@pjd0014Patrick joined Camden Depot in the fall of 2015, following two years writing for Baltimore Sports & Life. He is interested in data analysis and forecasting, and cultivates those skills with analysis aimed at improving the performance of the Orioles (should they ever listen).

Nate Delong - Writer@OriolesPGNate created and wrote for Orioles Proving Ground prior to joining Camden Depot in the middle of 2013. His baseball resume includes working as a scorer for Baseball Info Solutions and as a Video Intern for the Baltimore Orioles. His actual resume is much less interesting.

Matt Perez - Writer@FanOfLaundryMatt joined Camden Depot after the 2013 season. He is a data analyst/programmer in his day job and uses those skills to write about the Orioles and other baseball related topics.

Joe Reisel - WriterJoe has followed the Norfolk Tides now for 20 seasons. He currently serves as a Tides GameDay datacaster for milb.com and as a scorer for Baseball Info Solutions (BIS). He is computer programmer/analyst by day.

Joe Wantz - WriterJoe is a baseball and Orioles fanatic. In his spare time, he got his PhD in political science and works in data and analytics in Washington DC.